From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [kvm-ppc-devel] RFC/patch portability: split kvm_vm_ioctl v2 Date: Fri, 26 Oct 2007 11:08:30 +0200 Message-ID: <4721AE8E.6060900@qumranet.com> References: <1192192452.7630.16.camel@cotte.boeblingen.de.ibm.com> <1193327325.8345.9.camel@cotte.boeblingen.de.ibm.com> <1193327326.3284.2.camel@izike-woof.qumranet.com> <1193329322.28279.21.camel@basalt> <472114B6.6080000@qumranet.com> <1193345465.28279.47.camel@basalt> <4721A185.1070808@qumranet.com> <4721A3A3.8020504@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org" , kvm-ppc-devel , Hollis Blanchard , "Zhang, Xiantao" To: carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Return-path: In-Reply-To: <4721A3A3.8020504-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Carsten Otte wrote: > Avi Kivity wrote: > >> Hollis Blanchard wrote: >> >>> On Fri, 2007-10-26 at 00:12 +0200, Izik Eidus wrote: >>> >>> >>>> ok i was thinking, >>>> maybe we can rewrite the way kvm hold memory so more code would be shared, >>>> lets say we throw away all the slots and arch depended stuff, and we let kvm >>>> just hold the userspace allocated memory address, >>>> >>>> >>> With that approach, how would you create a sparse (guest physical) >>> memory map in userspace? I guess you would need to use repeated >>> mmap(MAP_FIXED), and that's starting to look very brittle. >>> >>> >>> >> It can't work on i386 due to the limited host virtual address space. >> > That's why memory allocation/preparation needs to be arch dependent: > i386 needs a memory layout different from userspace page table due to > your argument, and s390 needs to use the userspace page table due to > hardware features we want to exploit. > As Xiantao pointed out, x86 and ia64 can share the same memory setup > code. But s390 and ppc don't. Therefore, I vote for putting it into > x86 for now, and come up with an approach to share between x86 and > ia64 later on. > But can't s390 and ppc use a subset? If you limit the number of memory slots to one, it's equivalent to base + limit. No? -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/